The present invention relates to an operational amplifier circuit, a driving circuit and a driving method.
Conventionally, as a liquid crystal panel (electro-optical device) which is used for an electronic equipment such as a portable telephone, there have been known a single matrix type liquid crystal panel and an active matrix type liquid crystal panel which uses switching elements such as thin film transistors (abbreviated as TFT hereinafter).
Although the single matrix type is advantageous compared to the active matrix type with respect to a point that the lowering of power consumption can be easily obtained, the single matrix type has a disadvantage that the multi-colorization and the moving picture display are difficult. With respect to a technique for lowering the power consumption in the single matrix type, there has been known a conventional technique disclosed in Japanese Patent Application Laid-open No.7-98577, for example.
On the other hand, although the active matrix type has an advantage that this type is suitable for the multi-colorization and the moving picture display, the active matrix type has a disadvantage that the lowering of the power consumption is difficult.
Recently, in the field of the portable type electronic equipment such as a portable telephone set, the demand for multi-colorization and moving picture display has been increasing to provide images of high quality. Accordingly, in place of the single matrix type liquid crystal panel which has been used heretofore, the active matrix type liquid crystal panel is now popularly used.
However, with respect to the active matrix type liquid crystal panel used in the portable type electronic equipment, to cope with the demand for the alternating current driving of the liquid crystal and the lowering of voltage of power sources, a voltage level of counter electrodes (common electrodes) facing pixel electrodes in an opposed manner is inverted every scanning period, for example. Accordingly, due to the large charging/discharging of a liquid crystal panel and an operation current of an operational amplifier circuit which drives an analogue voltage, there has been a drawback that the realization of the lowering of power consumption is less than optimal.